125 Wistar rats were divided into five groups randomly. The experimental period was 20 weeks. The results showed that both in the rats drinkcd water containing 6mM Li_2CO_3. and the rats with iodine-deficiency alone, their thyroid gland increased in weight and showed a pattern of hyperplatic goitre; their serum T, dropped which T_3 was increased. These changes were more marked in the rats with iodine deficiency and the activity of thyroid superoxidas strengthened. But in the rats that drinked water containing 6mM Li_2CO_3 there was more colloid in the follicular lumens of the thyroid. Under the condition of iodine deficiency, the rats that drinkcd water containing 3mM and 6mM Li_2CO_3 had larger and heavier thyroid gland, and their serum T_4 dropped which T_3 remained normal. Compared with the rats which had iodine deficiency along, their thyroid glands showed a typical picture of colloid goitrc. In the iodine deficiency rats which drinked water containing 3mM Li_2CO_3 the change of the thyroid gland was even more marked.

Objective: This experiment was designed to study the change of nitric oxide (NO) content in different parts of brain in rats suffering from iodine deficiency(ID) and hypothyroidism since their fetal period. Methods: Iodine deficiency animal model was made and NO content in hippocampus(HPC), cerebellum (CE) and cortex(CO) were measured by using NO test kit. Results: Urinary iodine and serum T 3?T 4 concentrations significantly decreased and learning-memory capacity was impaired in ID rats. NO content was significantly lower in HPC and CE in ID rats than in control rats.(HPC:11.61?2.31/2.3?1 18 ?mol/g Prot;CE:10.77?5.16/4.70?1.95 ?mol/g Prot).No difference was found in cortex. Conclusion: Iodine deficiency and hypothyroidism since fetal period could affect NO level in rat brain. Different parts of brain have different sensitivity to ID and hypothyroidism.The changes of NO content in hippocampus may contribute to the learning-memory impairment in ID rats.